Kindly help me out with viterbi algorithm coding....

Question

Hi everybody,
V r doing a project on Spread Spectrum image steganography. One of our module is Low Rate ECC.We plan to do it using convolutional codes using viterbi algorithm.we have a problem in implementing it.Please help me out with the coding .

Answer 1

U would also be requiring Diagram.java
import java.awt.Color;
import java.awt.Graphics;
class Diagram
Diagram()
competitors = new int[20][27];
Letters = "abcdefghijklmnopqrstuvwxyz";
status = "";
x = 10;
y = 70;
no_letters = 0;
word_viable = true;
int[] Get_survivors(String s, int i)
int ai[] = new int[27];
float af[][] = Read_prob.reading_bigrams();
float af1[][] = Read_prob.reading_conf_matrix(i);
float af2[][] = new float[27][27];
float af3[][] = new float[27][27];
int ai1[][] = new int[27][27];
float af4[] = new float[27];
for(int l = 0; l < 27; l++)
af3[0][l] = 0.0F;
af4[l] = 100000F;
ai[l] = 0;
int k = s.length();
int j = s.charAt(0) - 96;
if(j < 0)
j += 32;
for(int i1 = 1; i1 < 27; i1++)
af3[0][i1] = -(af[27][i1] + af1[j][i1]);
float f = 100000F;
for(int j1 = 1; j1 < k; j1++)
j = s.charAt(j1) - 96;
if(j < 0)
j += 32;
for(int k1 = 1; k1 < 27; k1++)
for(int i2 = 1; i2 < 27; i2++)
af2[k1][i2] = af3[j1 - 1][i2] - (af[i2][k1] + af1[j][k1]);
if(af2[k1][i2] < af4[k1])
af4[k1] = af2[k1][i2];
ai1[j1 - 1][k1] = i2;
for(int j2 = 1; j2 < 27; j2++)
af3[j1][j2] = af4[j2];
af4[j2] = 100000F;
for(int l1 = 1; l1 < 27; l1++)
af2[k][l1] = af3[k - 1][l1] - af[l1][27];
if(af2[k][l1] < f)
f = af2[k][l1];
ai[k - 1] = l1;
j = ai[k - 1];
for(int k2 = k - 2; k2 >= 0; k2--)
ai[k2] = ai1[k2][j];
j = ai[k2];
Sort_q(af3, k);
return ai;
void Sort_q(float af[][], int i)
boolean flag = false;
int j = 0;
float f = 100000F;
for(int k = 0; k < i; k++)
for(int l = 0; l < 10; l++)
for(int i1 = 1; i1 < 27; i1++)
if(af[k][i1] < f)
f = af[k][i1];
j = i1;
competitors[k][l] = j;
af[k][j] = 100000F;
f = 100000F;
void Table(Graphics g, int i, String s)
int ai[] = Get_survivors(s, i);
int ai1[] = new int[20];
int ai2[] = new int[20];
no_letters = s.length();
x = 500 / no_letters - no_letters;
for(int j1 = 0; j1 < no_letters; j1++)
x += 35;
y = 80;
int l = x;
int i1 = y;
boolean flag = false;
g.setColor(Color.red);
int j = s.charAt(j1) - 97;
if(j < 0)
j += 32;
g.drawChars(Survivor, j, 1, x + 5, y + 11);
g.setColor(Color.blue);
g.drawRect(x, y, 16, 14);
y += 17;
for(int k1 = 0; k1 < 10; k1++)
int k = competitors[j1][k1];
if(word_viable)
g.setColor(Color.green);
g.drawRect(x, y, 16, 14);
g.setColor(Color.red);
g.drawChars(Survivor, k - 1, 1, x + 5, y + 11);
if(k == ai[j1])
flag = true;
if(k == j + 1)
ai1[j1] = l + 17;
ai2[j1] = i1 + 7;
} else
g.setColor(Color.blue);
g.drawRect(x, y, 16, 14);
g.setColor(Color.green);
g.drawRect(l, i1, 16, 14);
ai1[j1] = x + 17;
ai2[j1] = y + 7;
} else
if(!flag)
ai1[j1] = l + 17;
ai2[j1] = i1 + 7;
y += 17;
for(int l1 = 0; l1 < no_letters - 1; l1++)
g.setColor(Color.blue);
g.drawLine(ai1[l1], ai2[l1], ai1[l1 + 1] - 18, ai2[l1 + 1]);
g.drawChars(Survivor, ai[l1] - 1, 1, ai1[l1] - 12, y + 17);
g.drawChars(Survivor, ai[no_letters - 1] - 1, 1, ai1[no_letters - 1] - 12, y + 17);
void Trellis(Graphics g, int i, String s)
int ai[] = Get_survivors(s, i);
int ai1[] = new int[20];
int ai2[] = new int[20];
no_letters = s.length();
x = 500 / no_letters;
for(int k = 0; k < no_letters; k++)
x += 35;
y = 60;
for(int l = 0; l < 26; l++)
g.setColor(Color.green);
if(word_viable)
int j = Survivor[l] - 96;
if(ai[k] == j)
g.setColor(Color.blue);
ai1[k] = x + 17;
ai2[k] = y + 7;
g.drawRect(x, y, 16, 14);
g.setColor(Color.red);
g.drawChars(Survivor, l, 1, x + 5, y + 11);
y += 17;
for(int i1 = 0; i1 < no_letters - 1; i1++)
g.setColor(Color.blue);
g.drawLine(ai1[i1], ai2[i1], ai1[i1 + 1] - 18, ai2[i1 + 1]);
g.drawChars(Survivor, ai[i1] - 1, 1, ai1[i1] - 12, y + 17);
g.drawChars(Survivor, ai[no_letters - 1] - 1, 1, ai1[no_letters - 1] - 12, y + 17);
void delete()
for(int i = 0; i < no_letters; i++);
public String status;
public int competitors[][];
public String Letters;
public char Survivor[] = {
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z'
public int x;
public int y;
public boolean word_viable;
public int no_letters;
private Read_prob r_prob;
}